This proposed research program is a direct extension of our earlier programs with the same fundamental goals: the investigation of reproduction, oogenesis and early embryonic development and the molecular mechanisms that control genetic activity. The recent developments in our ability to study both individual gene activity and the organization of gene regions at the sequence level will be utilized to study embryonic development in several animal systems with continued focus on the sea urchin. We wish to continue our studies of germline transformation of sea urchin embryos including the development of new transformation vectors carrying a variety of unmodified and modified gene regions. Since transformed individuals will survive to sexual maturity we expect to be able to examine hereditary as well as immediate effects during development, metamorphosis and maturation. We plan to clone and utilize genes that are expressed at specific times and in specific cell types. Using transformation and a variety of other approaches we wish to continue our examination of the mechanism of gene regulation and the role of chosen genes in development. We plan to continue our work on the overall structure, fate and function of maternal poly(A) RNA. We hope to determine whether particular classes of genes are constituitively transcribed into nuclear RNA. We plan to study the molecular mechanisms of initial determination in sea urchin micromeres. We plan to compare the patterns of transcription of specific genes in lampbrush chromosomes of Xenopus oocytes. We intend, through the integration of the many available methods for molecular examination of gene expression, to examine the ways in which the system of regulation establishes the processes of oogenesis and embryonic morphogenesis.